The ideal lime dosage for the site was determined to be 0.5% of the dry soil weight to be mixed into the top six inches of soil. Approximately 600 cubic meters (m3 ) of soil (785 cubic yards [yd3]) on Bay 4 of Remagen Range was amended with hydrated lime [Ca(OH)2]

The treated area encompassed the primary impact area near the targets and the area immediately in front and adjacent to the primary impact area within Bay 4.

Several techniques were used to apply the lime amendment. These varied from simply opening bags and raking it to using a drop seed spreader.

The lime amendment was mixed into the soil to a depth of approximately 6 inches. Several mixing techniques were evaluated, including a garden rotor tiller, a small disc, a cultivator, and a rake.

A hydroseeder was used during the final lime application in order to evaluate the effect of concurrent liming and watering.

Purpose/Significance of Application:The objectives of the lime technology demonstration were to (1) validate that lime amendment of range soil could reduce or eliminate RDX, TNT, and degradation product concentrations in soil; (2) stabilize metals at the source area; and (3) significantly reduce migration of explosives and metals in solution. Results from this study will be used to provide an in situ or remote alternative for management of munitions constituents in soils on HGRs.

Regulatory Requirements/Cleanup Goals:
The primary performance criteria for the site include:
1) Achieve greater than a 90% reduction of RDX and TNT concentrations in runoff water compared to baseline and control conditions.
2) Achieve greater than a 90% reduction of RDX and TNT concentrations in soil pore water compared to baseline and control conditions.
3) Reduce total and dissolved phase metal concentrations in runoff water below control levels.
4) Reduce the concentration of phase metals in soil and pore water to below control levels.
5) Maintain control of soil pH levels (pH > 10.5 in source area; pH < 12.5 outside of source area).
6) Reduce RDX and TNT concentrations within the source area to below baseline and control levels.

Results:Data from the demonstration site indicated the following:

RDX was transformed by the alkaline hydrolysis reaction, and soil concentrations were reduced by more than 90%.

There was a 77% reduction in RDX concentration in pore water. The average pore water RDX concentration was consistently less in Bay 4 (lime applied) than in Bay 2 (control).

No TNT was detected in Bay 4 soils.

All of the phase metals analyzed in Bay 4 soil demonstrated a significant decrease in concentration (Fe, Cr, Mn, and V) or no change in concentration (Zn, Pb, and Ni).

The reactive impact area of the bay was maintained at a pH over 10.5. The pH of soil pore water and the surface water runoff remained near neutral.

The surface soil pH in the offsite area collecting this water averaged 7.4, approximately 1 standard unit (SU) above the control bay. Therefore, there was no evidence of impact from the lime outside the treated area. Air monitoring results indicated that the Calcium (Ca) levels in the air samples from the limed bay were similar to the Ca levels in air samples from the control bay.

Cost Factors:The cost of lime amendment per annum was $19 to $54/m3 ($25 to $71/yd3) of soil treated.

Description:The application of hydrated lime to a hand grenade range (HGR) to provide a mechanism for both metals immobilization and explosives transformation was demonstrated at the Fort Jackson, South Carolina, Remagen HGR. This area is located in the upper Atlantic Coastal Plain geologic province of South Carolina, characterized by low elevation and sandy hills. Live-fire training at the site created a source zone for munitions constituents such as metals and explosives. The contaminants produced by hand grenades used during this training include: RDX, TNT, and Fe and Zn.

Hydrated lime, Ca(OH)2, was chosen as the soil amendment based on its ability to increase soil pH to the range necessary to transform explosives to environmentally friendly end products and its ability to stabilize metals. The hydrated lime was mixed into the top six inches of soil on Bay 4 of the Remagen Range. The treated area encompassed the primary impact area near the targets and the area immediately in front of, adjacent to, the primary impact area.

During the course of the 20-month demonstration, soil, pore water, surface water, and air samples were collected to determine the effectiveness of lime to reduce migration of munitions constituents from the range. Monitoring of the soil and surface water was performed for a total of 20 months from December 2005 to June 2007. This period included 3 months of baseline monitoring and 17 months of monitoring following the lime applications. The results indicated that the application of lime can reduce the migration of munitions constituents from HGRs. RDX soil concentrations were reduced by more than 90% and the metals were stabilized in the soil.